When operating distribution systems of volumetric hydraulic machines, cavitation occurs due to the collapse of gas bubbles in the liquid, which causes noise. In planetary hydraulic machines, cavitation is especially pronounced due to the large number of distribution windows that form a rotating hydraulic field. The obtained mathematical dependencies describing the change in cavitation processes make it possible to determine the presence of cavitation at the design stage. It has been established that with a decrease in the gap between the windows, the noise level, which is an indicator of the presence of cavitation processes, decreases from 100 to 80 dB. At the same time, the distribution system ensures separation of high- and low-pressure zones, preserving high volumetric efficiency (0.95) is maintained. With a negative gap value, the high- and low-pressure zones overlap, and the operating noise decreases by 2%. The overlap area is 1.73 mm2, which leads to a 5% decrease in volumetric efficiency. Studies of a serial hydraulic motor show that when changing the rotation speed, the noise of its operation increases from 91 to 102 dB. For a modernized hydraulic motor, the noise is 81 dB. Therefore, a modernized distribution system that does not have a gap between the distribution windows is recommended for designing the entire unified series of planetary hydraulic motors.